Ceramic electronic component, ceramic electronic component manufacturing method, and ceramic electronic component-mounting circuit board

ABSTRACT

Disclosed is a ceramic electronic component having external electrodes on each of opposed end portions of a rectangular parallelepiped component body. A first direction dimension, a second direction dimension and a third direction dimension of the component body satisfy a condition of second direction dimension &gt;first direction dimension &gt;third direction dimension. The external electrodes are of a five-face type having a first face portion, a second face portion, a third face portion, a fourth face portion and a fifth face portion. At least one edge of the fourth face portion and the fifth face portion of the external electrode has a recess portion recessed from the edge toward the first face portion. Both side portions in the third direction of the recess portion are covering portions which cover ridge portions of the two faces in the second direction of the component body

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims benefit of priority fromJapanese Patent Application No. 2018-193502, filed on Oct. 12, 2018, theentire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a ceramic electronic component such asa multilayer ceramic capacitor, a manufacturing method for the ceramicelectronic component, and a ceramic electronic component-mountingcircuit board in which the ceramic electronic component is mounted on acircuit board.

Generally, a ceramic electronic component such as a multilayer ceramiccapacitor has external electrodes on each of lengthwise end portions ofa rectangular parallelepiped component body satisfying a condition oflength direction dimension >width direction dimension, but recently, aso-called LW-reversed type ceramic electronic component is also known,in which a dimensional relationship between the length directiondimension and the width direction dimension is reversed (see FIG. 4 inJapanese Patent Laid-Open No. 2014-146669).

On the other hand, with thinning of electronic apparatuses such assmartphones and notebook computers, ceramic electronic componentsmounted on circuit boards are required to correspond to low-heightmounting (low mounting height). That is, it is necessary to reduce aheight direction dimension of a component body for satisfying the aboverequirements in the LW-reversed type ceramic electronic component.

Incidentally, since the LW-reversed type ceramic electronic componenthas external electrodes on each of lengthwise end portions of arectangular parallelepiped component body satisfying a condition ofwidth direction dimension >length direction dimension, a bendingstrength according to a direction intersecting with the length directionis generally higher than that of a general type ceramic electroniccomponent having the same external dimensions of the component body, ina case of a five-face type external electrode (so-called four-corneredcap shape, having a first face portion formed on one face in a lengthdirection of the component body, a second face portion and a third faceportion formed on a part of two faces in a height direction of thecomponent body, and a fourth face portion and a fifth face portionformed on a part of two faces in a width direction of the componentbody: see FIG. 4 in Japanese Patent Laid-Open No. 2014-146669).

However, even in the case of the LW-reversed type ceramic electroniccomponent (the external electrode is of the aforementioned five-facetype), when the height direction dimension of the component body isreduced, e.g., to 150 μm or smaller for satisfying the aforementionedrequirements, cracks extends in the height direction especially on thetwo faces in the width direction of the component body, i.e., aso-called crack extension phenomenon is easily caused due to applicationof an external force that bends the ceramic electronic component in adirection intersecting with the length direction. As a result, there isa growing concern that the ceramic electronic component has dysfunction.

SUMMARY

It is desirable to provide a ceramic electronic component, a ceramicelectronic component manufacturing method, and a ceramic electroniccomponent-mounting circuit board, which can suppress a crack extensionphenomenon causable in the component body even in a case where theheight direction dimension of the LW-reversed type component body isreduced.

According to an embodiment of the present disclosure, there is provideda ceramic electronic component having external electrodes on each ofopposed end portions of a rectangular parallelepiped component body, inwhich under a condition that a facing direction of opposed two faces ofthe component body is defined as a first direction, a facing directionof other opposed two faces is defined as a second direction, and afacing direction of the remaining opposed two faces is defined as athird direction, and dimensions along the respective directions aredefined as a first direction dimension, a second direction dimension anda third direction dimension, respectively, the first directiondimension, the second direction dimension and the third directiondimension of the component body satisfy a condition of second directiondimension >first direction dimension >third direction dimension,

the external electrodes are of a five-face type having a first faceportion formed on one face in the first direction of the component body,a second face portion and a third face portion formed on a part of twofaces in the third direction of the component body, and a fourth faceportion and a fifth face portion formed on a part of two faces in thesecond direction of the component body,

at least one edge of the fourth face portion and the fifth face portionof the external electrode has a recess portion recessed from the edgetoward the first face portion, and both side portions in the thirddirection of the recess portion are covering portions which cover ridgeportions of the two faces in the second direction of the component body.

The ceramic electronic component manufacturing method according to thepresent disclosure is a method for manufacturing the aforementionedceramic electronic component, in which a process for producing theexternal electrode includes: forming, on a surface of the componentbody, a base conductor layer corresponding to the first face portion,the second face portion and the third face portion, and a fourth faceportion and a fifth face portion having the recess portions and thecovering portions; and forming, on the surface of the base conductorlayer, at least one covering conductor layer.

Furthermore, in the ceramic electronic component-mounting circuit boardaccording to the present disclosure, the aforementioned ceramicelectronic component is mounted on the circuit board.

The ceramic electronic component, the ceramic electroniccomponent-manufacturing method, and the ceramic electroniccomponent-mounting circuit board according to the present disclosure cansuppress the crack extension phenomenon causable in the component bodyeven in a case where the ceramic electronic component is of aLW-reversed type and the height direction dimension of the componentbody is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view of a ceramic electronic component (multilayerceramic capacitor) according to an embodiment of the present disclosure,FIG. 1B is a bottom view of the ceramic electronic component (multilayerceramic capacitor) according to the embodiment of the presentdisclosure, FIG. 1C is a side view in a second direction d2 of theceramic electronic component (multilayer ceramic capacitor) according tothe embodiment of the present disclosure, and FIG. 1D is a side view ina first direction dl of the ceramic electronic component (multilayerceramic capacitor) according to the embodiment of the presentdisclosure;

FIG. 2A is a sectional view along line S1-51 of FIG. 1A, and FIG. 2B isa sectional view along line S2-S2 of FIG. 1A;

FIG. 3A is an enlarged view of FIG. 1C, and FIG. 3B is a sectional viewalong line S3-S3 of FIG. 3A;

FIG. 4A and FIG. 4B are drawings for illustrating an example of anexternal electrode producing method;

FIG. 5 is a drawing for illustrating an example of a method for mountingthe ceramic electronic component depicted in FIGS. 1A, 1B, 1C and 1D ona circuit board;

FIG. 6 is a drawing for illustrating an effect obtained by the ceramicelectronic component depicted in FIGS. 1A, 1B, 1C and 1D;

FIG. 7A and FIG. 7B are drawings depicting modification examples of ashape of a recess portion on the external electrode depicted in FIGS.1A, 1B, 1C and 1D; and

FIGS. 8A, 8B and 8C are drawings depicting modification examples ofshapes of a second face portion and a third face portion on the externalelectrode depicted in FIGS. 1A, 1B, 1C and 1D.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For convenience sake, in the following explanation, a facing directionof opposed two faces of a component body 11 depicted in FIGS. 1A, 1B, 1Cand 1D (lateral direction in FIG. 1A, FIG. 1B and FIG. 1C) is denoted as“first direction d1,” a facing direction of other opposed two faces(vertical direction in FIG. 1A and FIG. 1B, and lateral direction inFIG. 1D) is denoted as “second direction d2,” a facing direction of theremaining opposed two faces (vertical direction in FIG. 1C and FIG. 1D)is denoted as “third direction d3.”

In addition, a dimension along the first direction dl of eachconstituent is denoted as “first direction dimension D1 [symbol ofconstituent],” a dimension along the second direction d2 is denoted as“second direction dimension D2 [symbol of constituent],” and a dimensionalong the third direction d3 is denoted as “third direction dimension D3[symbol of constituent].” Note that, when explaining internal electrodelayers 11 a, dielectric layers 11 b, dielectric margin portions 11 c and11 d, external electrodes 12, and the like, a term “thickness” isoptionally used for promoting understanding. Incidentally, a numericalvalue cited as each dimension refers to a design basic dimension anddoes not include a manufacture dimensional tolerance.

FIGS. 1A, 1B, 1C, 1D, 2A, 2B, 3A, 3B, 4A, 4B, 5 and 6 relate to aceramic electronic component 10 in which the present disclosure isapplied to the multilayer ceramic capacitor. The ceramic electroniccomponent 10 depicted in FIGS. 1A, 1B, 1C, 1D, 2A, 2B, 3A, 3B, 4A, 4B, 5and 6 falls under the LW-reversed type described in BACKGROUND, alsocorresponds to low-height mounting (low mounting height), and has theexternal electrodes 12 on each end portion in the first direction dl ofthe rectangular parallelepiped component body 11.

A first direction dimension D1 [11], a second direction dimension D2[11] and a third direction dimension D3 [11] of the component body 11satisfy a condition of second direction dimension D2 [11] >firstdirection dimension D1 [11] >third direction dimension D3 [11].Incidentally, each corner portion (symbol is omitted) and each ridgeportion RP of the component body 11 are somewhat rounded.

In addition, the component body 11 incorporates a capacitive portion(symbol is omitted) as a functional portion in which a plurality ofrectangular internal electrode layers 11 a are laminated in the thirddirection d3 through the dielectric layers 11 b. As depicted in FIG. 2Aand FIG. 2B, this capacitive portion is surrounded by the dielectricmargin portions 11 c on the both sides in the third direction d3 anddielectric margin portions 11 d on the both sides in the seconddirection d2.

Furthermore, as depicted in FIG. 2A, the plurality of internal electrodelayers 11 a are alternately shifted in the first direction d1, and oneedge in the first direction d1 of the internal electrode layer 11 aodd-numbered from the top in FIG. 2A is connected to a first faceportion 12 a of one external electrode 12, and the other edge in thefirst direction d1 of the internal electrode layer 11 a even-numberedfrom the top in FIG. 2A is connected to the first face portion 12 a ofthe other external electrode 12.

The third direction dimension D3 [11] of the component body 11 can be,e.g., within a range of 60 to 120 μm, or 25 to 60 μm in consideration oflow-height mounting (low mounting height) of the ceramic electroniccomponent 10. The first direction dimension D1 [11] and the seconddirection dimension D2 [11] of the component body 11 are notparticularly limited in light of the relationship with low-heightmounting (low mounting height) of the ceramic electronic component 10.However, in light of a balance with the third direction dimension D3[11], the first direction dimension D1 [11] can be, e.g., within a rangeof 200 to 800 μm, and the second direction dimension D2 [11] can be,e.g., within a range of 400 to 1600 μm.

Thicknesses of the internal electrode layer 11 a and the dielectriclayer 11 b can be, e.g., within a range of 0.3 to 4 pm in considerationof low-height mounting (low mounting height) of the ceramic electroniccomponent 10. Thicknesses of the dielectric margin portions 11 c and 11d can be, e.g., within a range of 3 to 30 μm in consideration oflow-height mounting (low mounting height) of the ceramic electroniccomponent 10.

Incidentally, a first direction dimension D1 [11 a] and a seconddirection dimension D2 [11 a] of the internal electrode layer 11 a, andthe total number of the internal electrode layers 11 a can bearbitrarily changed depending on external dimensions, a desiredcapacitance value, and the like of the ceramic component body 11. Thedesired capacitance value of the ceramic electronic component 10corresponding to low-height mounting (low mounting height) can be, e.g.,within a range of 0.1 to 0.3 μF, or 0.3 to 1.0 μF.

Examples of main ingredients of the dielectric layer 11 b and thedielectric margin portions 11 c and 11 d include dielectric ceramicssuch as barium titanate, strontium titanate, calcium titanate, magnesiumtitanate, calcium zirconate, calcium titanate zirconate, bariumzirconate, and titanium oxide. Examples of the main ingredient of theinternal electrode layer 11 a include metals such as nickel, copper,palladium, platinum, silver, gold, and an alloy thereof.

Incidentally, the main ingredient of the dielectric layer 11 b and themain ingredient of the dielectric margin portion 11 c may be differentfrom each other, or otherwise the main ingredient of the dielectriclayer 11 b, the main ingredient of the dielectric margin portion 11 c onone side in the third direction d3, and the main ingredient of thedielectric margin portion 11 c on the other side in the third directiond3 may be different from each other.

On the other hand, the external electrode 12 is of a five-face typehaving the first face portion 12 a formed on one face in the firstdirection dl of the component body 11, a second face portion 12 b and athird face portion 12 c formed on a part of two faces in the thirddirection d3 of the component body 11, and a fourth face portion 12 dand a fifth face portion 12 e formed on a part of two faces in thesecond direction d2 of the component body 11. That means, in the ceramicelectronic component 10, any face in the third direction d3 can be usedas a mounting face (connection face). Incidentally, in a view of thesecond face portion 12 b and the third face portion 12 c from the thirddirection d3, the two corner portions (symbol is omitted) on the side ofthe first face portion 12 a are slightly rounded (e.g., a curvatureradius is within a range of 10 to 150 μm), or otherwise taperedcommensurately with the roundness.

As will be explained later with reference to FIGS. 8A, 8B and 8C, theroundness of the two corner portions on the edge sides of the secondface portion 12 b and the third face portion 12 c can be formed largerthan the roundness of the two corner portions on the side of the firstface portion 12 a.

Maximum values of a first direction dimension D1 [12 b] of the secondface portion 12 b, a first direction dimension D1 [12 c] of the thirdface portion 12 c, and a first direction dimension D1 [12 d] of thefourth face portion 12 d are equal to or substantially equal to amaximum value of a first direction dimension D1 [12 e] of the fifth faceportion 12 e.

As will be explained later with reference to FIGS. 8A, 8B and 8C, firstdirection dimensions D1 [12 b′&12 c] of a second face portion 12 b′ anda third face portion 12 c′ can be made larger than the first directiondimensions D1 [12 d&12 e] of the fourth face portion 12 d and the fifthface portion 12 e.

In addition, at least one of or preferably both of the edges of thefourth face portion 12 d and the fifth face portion 12 e have recessportions 12 d 1 and 12 e 1 recessed from the edges toward the first faceportion 12 a. Both side portions in the third direction d3 of the recessportions 12 d 1 and 12 e 1 are covering portions 12 d 2 and 12 e 2 forcovering the ridge portions RP on the two faces in the second directiond2 of the component body 11.

That means, since the fourth face portion 12 d is continuous with thesecond face portion 12 b and the third face portion 12 c, the continuouspart is the covering portion 12 d 2 for covering the ridge portion RP,and since the fifth face portion 12 e is also continuous with the secondface portion 12 b and the third face portion 12 c, the continuous partis the covering portion 12 e 2 for covering the ridge portion RP.

Incidentally, a shape of the recess portions 12 d 1 and 12 e 1 viewedfrom the second direction d2 is rectangular.

As will explained later with reference to FIGS. 7A and 7B, recessportions 12 d 3 and 12 e 3 and recess portions 12 d 5 and 12 e 5 viewedfrom the second direction d2 may be V-shaped or U-shaped.

Furthermore, the recess portion 12 d 1 is preferably formed at themiddle in the third direction d3 of the edge of the fourth face portion12 d, and the recess portion 12 e 1 is preferably formed at the middlein the third direction d3 of the edge of the fifth face portion 12 e.The reason why it is preferable to form the recess portion at the middleof the third direction d3 is because third direction dimensions D3 [12 d2] of the covering portions 12 d 2 present on both sides in the thirddirection d3 of the recess portion 12 d 1 should be equal to each otheras much as possible, and the third direction dimensions D3 [12 e 2] ofthe covering portions 12 e 2 present on both sides in the thirddirection d3 of the recess portion 12 e 1 should be equal to each otheras much as possible.

The first direction dimensions D1 [12 b, 12 c, 12 d&12 e] of the secondface portion 12 b, the third face portion 12 c, the fourth face portion12 d, and the fifth face portion 12 e can be, e.g., within a range of1/10 to 4/10 of the first direction dimension D1 [11] of the componentbody 11.

In a case where the ceramic electronic component 10 is mounted on acircuit board CB (see FIG. 5), the second face portion 12 b or the thirdface portion 12 c faces a conductive pad CBa of the circuit board CB,and therefore the first direction dimensions D1 [12 b&12 c] of thesecond face portion 12 b and the third face portion 12 c are preferablyensured to be at least 50 μm. In addition, for the purpose of avoidingshort-circuiting between the second face portions 12 b or between thethird face portions 12 c due to a solder SOL in the soldering processduring mounting, a distance between the second face portions 12 b in thefirst direction and a distance between the third face portions 12 c inthe first direction are preferably ensured to be at least 100 μm.

First direction dimensions D1 [12 d 1&12 e 1] of the recess portions 12d 1 and 12 e 1 can be, e.g., within a range of 5% to 95% of the firstdirection dimensions D1 [12 d&12 e] of the fourth face portion 12 d andthe fifth face portion 12 e. When the first direction dimensions D1 [12d 1&12 e 1] of the recess portions 12 d 1 and 12 e 1 are smaller than 5%of the first direction dimensions D1 [12 d&12 e] of the fourth faceportion 12 d and the fifth face portion 12 e, an effect described below(suppression of crack extension) is hardly obtained, and when they arelarger than 95%, area ratios of the recess portions 12 d 1 and 12 e 1are large, and therefore a desired strength of the fourth face portion12 d and the fifth face portion 12 e is hardly obtained.

When emphasizing suppression of the crack extension, the first directiondimensions D1 [12 d 1&12 e 1] of the recess portions 12 d 1 and 12 e 1are within a range of 5% to 15%, preferably 15% to 65%, more preferably65% to 95% of the first direction dimensions D1 [12 d&12 e] of thefourth face 12 d portion and the fifth face portion 12 e.

The ranges of the third direction dimensions D3 [12 d 1&12 e 1] of theopen ends of the recess portions 12 d 1 and 12 e 1 are not particularlylimited as long as they are smaller than the third direction dimensionsD3 [12 d&12 e] of the fourth face portion 12 d and the fifth faceportion 12 e, in other words, as long as the covering portions 12 d 2and 12 e 2 are present on both sides in the third direction d3 of therecess portions 12 d 1 and 12 e 1. In addition, the third directiondimensions at the middle in the first direction between the open end andthe impasse portion of the recess portions 12 d 1 and 12 e 1 arepreferably 40% to 95%, more preferably 50% to 85% of the third directiondimensions of the fourth face portion 12 d and the fifth face portion 12e.

Thicknesses of the first face portion 12 a, the second face portion 12b, the third face portion 12 c, the fourth face portion 12 d, and thefifth face portion 12 e of the external electrode 12 can be, e.g.,within a range of 10 to 18 μm, or 2 to 10 μm in consideration oflow-height mounting (low mounting height) of the ceramic electroniccomponent 10.

In addition, the external electrode 12 has a multilayer structureincluding a base conductor layer and at least one covering conductorlayer for covering the surface of the base conductor layer. The numberof the covering conductor layer is not particularly limited, but may be,e.g., 1 to 4 in light of a balance with the thickness of each faceportion 12 a to 12 e of the external electrode 12. The main ingredientof the external electrode 12 will be explained in the following examplesof a manufacturing method including a layer configuration and aformation procedure.

Herein, a preferable example of the manufacturing method for theaforementioned ceramic electronic component 10, particularly apreferable example of the production method for the external electrode12 will be explained.

The ceramic electronic component 10 is manufactured mainly by

-   a process for producing the component body 11, and-   a process for producing the external electrodes 12 on each end    portion in the first direction dl of the component body 11.

The process for producing the component body 11 includes: a step offorming a multiple-patterning unbaked multilayer sheet by appropriatelylaminating and pressure-bonding a ceramic green sheet having no internalelectrode layer pattern and a ceramic green sheet having the internalelectrode layer pattern; a step of forming a unbaked chip correspondingto the component body 11 by chopping the unbaked multilayer sheet; astep of grinding the unbaked chip; and a step of baking the unbaked chipunder an atmosphere and temperature profile according to a ceramicmaterial and a metal material.

The process of producing the external electrode 12 includes: a step offorming the base conductor layer on the surface of the component body;and a step of forming at least one covering conductor layer on thesurface of the base conductor layer. In a case where there are two ormore covering conductor layers, the first covering conductor layer isformed on the surface of the base conductor layer, and the second andsubsequent covering conductor layers are sequentially formed on thesurface of the antecedently formed covering conductor layer.

As an example, a case where the external electrode 12 has a four-layerconfiguration will be explained in detail with reference to FIGS. 4A and4B (internal electrode layers 11 a are not illustrated). First, a baseconductor layer CF1 having a shape corresponding to the first faceportion 12 a, the second face portion 12 b, the third face portion 12 c,the fourth face portion 12 d, and the fifth face portion 12 e is formedon the surface of the component body 11. A shape of a recess portion CF1a of the base conductor layer CF1 viewed from the second direction d2 isslightly smaller than the recess portions 12 d 1 and 12 e 1 of thefourth face portion 12 d and the fifth face portion 12 e. Then, a firstcovering conductor layer CF2 is formed on the surface of the baseconductor layer CF1, a second covering conductor layer CF3 is formed onthe surface of the first covering conductor layer CF2, and a thirdcovering conductor layer CF4 is formed on the surface of the secondcovering conductor layer CF3.

For forming the base conductor layer CF1 and the respective coveringconductor layers CF2 to CF4, the following methods can be selectivelyadopted: a so-called baking method in which a metal paste containing atleast a metal powder, an organic solvent and a synthetic resin binder isapplied by a procedure such as a screen printing method and a dippingmethod, dried and then baked; a dry plating method such as sputteringand vacuum deposition; and a wet plating method such as electroplatingor electroless plating. In light of a balance with the thicknesses ofthe respective face portions 12 a to 12 e of the external electrode 12,particularly with the thicknesses of the second face portion 12 b andthe third face portion 12 c, it is preferable that the base conductorlayer CF1 is formed by using the baking method and sputtering incombination or by sputtering, and the respective covering conductorlayers CF2 to CF4 are formed by electroplating in consideration of massproductivity.

In a case where forming the base conductor layer CF1 by using the bakingmethod and sputtering in combination, the main ingredients of the bakedfilm and the sputtered film can be, e.g., metals such as copper, nickel,silver, gold, platinum, palladium, tin, chromium, titanium, tantalum,tungsten, molybdenum, and an alloy thereof.

When forming the base conductor layer CF1 by using the baking method andsputtering in combination, first, a baked film is formed on one face inthe first direction d1 of the component body 11 so that the peripheryportion slightly wraps two faces in the second direction d2 and twofaces in the third direction d3, and subsequently a sputtered film whichis continuous with the baked film and has the recess portion CF1 adepicted in FIG. 4A is formed on the two faces in the second directiond2 and the two faces in the third direction d3 of the component body 11,and this sputtered film is used as the base conductor layer CF1. In acase where a desired sputtered film is hardly formed by singlesputtering, the sputtering may be conducted twice or more by changingthe direction of the component body 11, or the like.

On the other hand, in a case where the base conductor layer CF1 isformed by sputtering, the main ingredient of the sputtered film can be,e.g., the same metal as described above.

When forming the base conductor layer CF1 by sputtering, a sputteredfilm having the recess portion CF1 a depicted FIG. 4A is formed on oneface in the first direction d1, two faces in the second direction d2,and two faces in the third direction d3 of the component body 11, andthis sputtered film is used as the base conductor layer CF1. In a casewhere a desired sputtered film is hardly formed by single sputtering,the sputtering may be conducted twice or more by changing the directionof the component body 11, or the like.

There is no remarkable quality difference between the case of formingthe base conductor layer CF1 by using the baking method and sputteringin combination and the case of forming the base conductor layer CF1 bysputtering. However, so to speak, in the former case, an adhesiveness ofthe base conductor layer CF1 to the component body 11 can be enhanced bythe baked film included in the base conductor layer CF1. On the otherhand, in the latter case, the base conductor layer CF1 can be formedonly by sputtering, contributing to reduction of steps.

In a case where the respective covering conductor layers CF2 to CF4 areformed by electroplating, the main ingredient of the respective coveringconductor CF2 to CF4 can be, e.g., the same main ingredient as of thebase conductor layer CF1, but, in consideration of mutual adhesiveness,the main ingredient of the first covering conductor layer CF2 may bedifferent from the main ingredient of the base conductor layer CF1, themain ingredient of the second covering conductor layer CF3 may bedifferent from the main ingredient of the first covering conductor layerCF2, and the main ingredient of the third covering conductor layer CF3may be different from the main ingredient of the second coveringconductor layer CF2.

As an example, the main ingredient can be a combination of nickel as themain ingredient of the base conductor layer CF1, copper as the mainingredient of the first covering conductor layer CF2, nickel as the mainingredient of the second covering conductor layer CF3, tin as the mainingredient of the third covering conductor layer CF4.

Also in a case where the external electrode 12 has a two-layerconfiguration, a three-layer configuration, or a five-layerconfiguration different from the aforementioned four-layerconfiguration, the formation method and the main ingredients of the baseconductor layer and the covering conductor layer are the same as in thefour-layer configuration. In a case where the external electrodes 12 areconnected to the conductive pad CBa of the circuit board CB using thesolder SOL (see FIG. 5), the main ingredient of the outermost coveringconductor layer of the external electrode 12 having a two- to five-layerconfiguration is preferably tin which is most compatible with solder.

When the aforementioned ceramic electronic component 10 is mounted onthe circuit board CB, a soldering paste is applied to conductive padsCBa corresponding to the external electrodes 12 disposed on the circuitboard CB by printing or the like, and the ceramic electronic component10 is installed so that the third face portion 12 c of the externalelectrode 12 contacts the soldering paste, as depicted in FIG. 5 (a casewhere the lower face in FIG. 5 in the third direction d3 of the ceramicelectronic component 10 is used as the mounting face). Subsequently, thecircuit board CB equipped with the ceramic electronic component 10 isput into a reflow furnace (not depicted in the figure), and then,through a preheating step, a main heating step and a cooling step, theexternal electrodes 12 are connected to the conductive pad CBa via thesolder SOL.

In the aforementioned ceramic electronic component 10 mounted on thecircuit board CB, as depicted in FIG. 6, when an external force isapplied to the ceramic electronic component 10 so as to bend the ceramicelectronic component 10 in a direction intersecting with the firstdirection dl due to deflection of the circuit board CB (see two-dotchain lines in FIG. 6) and the like based on thermalexpansion/contraction, external force application, or the like, stressconcentrates to positions marked with x on the ceramic electroniccomponent 10 in FIG. 6.

Although the stress concentration can generally cause cracks, stresstransmission in the third direction d3 can be dispersed by the recessportions 12 d 1 and 12 e 1 even if the stress concentrates to thepositions marked with x in FIG. 6, because the recess portions 12 d 1and 12 e 1 recessed from the edge toward the first face portion 12 a areformed on at least one edge, preferably both edges of the fourth faceportion 12 d and the fifth face portion 12 e of the external electrode12. Thus, it is hard to cause a so-called crack extension phenomenon inwhich cracks extend straight in the third direction d3 on two faces inthe second direction d2 of the component body 11.

Furthermore, in a case where the recess portions 12 d 1 and 12 e 1 areon at least one edge, preferably both edges of the fourth face portion12 d and the fifth face portion 12 e of the external electrode 12, themolten solder spreads up to the surfaces of the recess portions 12 d 2and 12 e 2 of the fourth face portion 12 d and the fifth face portion 12e, but the up-spreading is likely to be blocked by the recess portions12 d 1 and 12 e 1. That means, in a case where the up-spreading isblocked, the solder SOL adheres to the surfaces of the fourth faceportion 12 d and the fifth face portion 12 e of the external electrode12 while avoiding the recess portions 12 d 1 and 12 e 1, as depicted inFIG. 5. Thus, this aspect can mitigate transmission in the thirddirection d3 of the stress concentrating to the positions marked with xin FIG. 6, and further suppress occurrence of the crack extensionphenomenon.

In addition, in a case where the recess portions 12 d 1 and 12 e 1 areon at least one edge, preferably on both edges of the fourth faceportion 12 d and the fifth face portion 12 e of the external electrode12, the solder SOL bridges between the fourth face portions 12 d orbetween the fifth face portions 12 e to enhance a possibility to avoidconduction between the fourth face portion 12 d and the fifth faceportion 12 e via the recess portions 12 d 1 and 12 e 1 in the solderingprocess, and also enhance a possibility to avoid conduction between thefourth face portion 12 d and the fifth face portion 12 e via the recessportions 12 d 1 and 12 e 1 on the basis of the migration.

Furthermore, in a case where the recess portions 12 d 1 and 12 e 1 areon at least one edge, preferably on both edges of the fourth faceportion 12 d and the fifth face portion 12 e of the external electrode12, the ridge portions RP on the two faces in the second direction ofthe component body 11 can be prevented from cracking compared to thecase of no covering portions 12 d 2 and 12 e 2 in a distributionprocess, a mounting process or the like of the ceramic electroniccomponent 10, because the covering portions 12 d 2 and 12 e 2 forcovering the ridge portions RP of the two faces in the second directiond2 of the component body 11 along the ridge portions RP are disposed onthe both sides in the third direction d3.

FIGS. 7A and 7B depict modification examples of the shapes of the recessportions 12 d 1 and 12 e 1 formed on the fourth face portion 12 d andthe fifth face portion 12 e of the external electrode 12 of the ceramicelectronic component 10. The recess portions 12 d 3 and 12 e 3 viewedfrom the second direction d2 depicted in FIG. 7A are V-shaped, andshapes of covering portions 12 d 4 and 12 e 4 on both sides in the thirddirection d3 are also slightly changed along with the V-shape. Toexplain the V-shape in other words, an angle formed by two straightlines running from the open end toward the end portion in the firstdirection is less than 90 degrees in the recess portion. In addition,the recess portions 12 d 5 and 12 e 5 viewed from the second directiond2 depicted in FIG. 7B are U-shaped, and shapes of covering portions 12d 6 and 12 e 6 on both sides in the third direction d3 are also slightlychanged along with the U-shape. To explain the U-shape in other words,the impasse portion is curved on the recess portion.

In a case where the rectangular recess portions 12 d 1 and 12 e 1 formedon the fourth face portion 12 d and the fifth face portion 12 e of theexternal electrode 12 of the aforementioned ceramic electronic component10 are replaced by the V-shaped recess portions 12 d 3 and 12 e 3depicted in FIG. 7A, and also replaced by the U-shaped recess portions12 d 5 and 12 e 5 depicted in FIG. 7B, the same effect as describedabove can be obtained.

FIGS. 8A, 8B and 8C depict modification examples of the shapes of thesecond face portion 12 b and the third face portion 12 c of the externalelectrode 12 of the ceramic electronic component 10. The first directiondimensions D1 [12 b′&12 c] of the second face portion 12 b′ and thethird face portion 12 c′ depicted in FIGS. 8A, 8B and 8C are larger thanthe first direction dimensions D1 [12 d&12 e] of the fourth face portion12 d and the fifth face portion 12 e. Ranges of values obtained bysubtracting the first direction dimensions D1 [12 d&12 e] from the firstdirection dimensions D1 [12 b′&12 c′], i.e., ranges of first directiondimensions D1 [12 b 1&12 c 1] of an overhang portion 12 b 1 of thesecond face portion 12 b′ and an overhang portion 12 c 1 of the thirdface portion 12 c′ can be, e.g., 1/20 to 1/2 of the first directiondimensions D1 [12 d&12 e] of the fourth face portion 12 d and the fifthface portion 12 e.

In addition, in a case where the first direction dimensions D1 [12 b′&12c] of the second face portion 12 b′ and the third face portion 12 c′ arelarger than the first direction dimensions D1 [12 d&12 e] of the fourthface portion 12 d and the fifth face portion 12 e, the roundness of thetwo corners (symbol is omitted) on the edge sides of the second faceportion 12 b′ and the third face portion 12 c′ can be made larger thanthe roundness of the two corners (symbol is omitted) on the side of thefirst face portion 12 a.

Even in a case where the second face portion 12 b and the third faceportion 12 c of the external electrode 12 on the aforementioned ceramicelectronic component 10 are changed to the second face portion 12 b′ andthe third face portion 12 c′ depicted in FIGS. 8A, 8B and 8C, the sameeffect as described above can be obtained.

Although the ceramic electronic component 10 in which the presentdisclosure is applied to the multilayer ceramic capacitor has beenexplained above, the present disclosure can also be applied to ceramicelectronic components other than the multilayer ceramic capacitor, e.g.,a multilayer ceramic varistor, a multilayer ceramic inductor, or thelike. That means, as long as the ceramic electronic component fallsunder the LW-reversed type described in BACKGROUND and also correspondsto the low-height mounting (low mounting height), the present disclosurecan be applied to the ceramic electronic component to obtain the sameeffect as described above.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2018-193502 filed in theJapan Patent Office on Oct. 12, 2018, the entire content of which ishereby incorporated by reference.

What is claimed is:
 1. A ceramic electronic component having external electrodes on each of opposed end portions of a rectangular parallelepiped component body, wherein under a condition that a facing direction of opposed two faces of the component body is defined as a first direction, a facing direction of other opposed two faces is defined as a second direction, and a facing direction of the remaining opposed two faces is defined as a third direction, and dimensions along the respective directions are defined as a first direction dimension, a second direction dimension and a third direction dimension, respectively, the first direction dimension, the second direction dimension and the third direction dimension of the component body satisfy a condition of second direction dimension >first direction dimension >third direction dimension, the external electrodes are of a five-face type having a first face portion formed on one face in the first direction of the component body, a second face portion and a third face portion formed on a part of two faces in the third direction of the component body, and a fourth face portion and a fifth face portion formed on a part of two faces in the second direction of the component body, at least one edge of the fourth face portion and the fifth face portion of the external electrode has a recess portion recessed from the edge toward the first face portion, and both side portions in the third direction of the recess portion are covering portions which cover ridge portions of the two faces in the second direction of the component body.
 2. The ceramic electronic component according to claim 1, wherein the recess portions are formed at a middle in the third direction of the edges of the fourth face portion and the fifth face portion.
 3. The ceramic electronic component according to claim 1, wherein first direction dimensions of the recess portions are within a range of 5% to 15% of first direction dimensions of the fourth face portion and the fifth face portion.
 4. The ceramic electronic component according to claim 1, wherein the first direction dimensions of the recess portions are within a range of 15% to 65% of the first direction dimensions of the fourth face portion and the fifth face portion.
 5. The ceramic electronic component according to claim 1, wherein the first direction dimensions of the recess portions are within a range of 65% to 95% of the first direction dimensions of the fourth face portion and the fifth face portion.
 6. The ceramic electronic component according to claim 1, wherein third direction dimensions of open ends of the recess portions are smaller than third direction dimensions of the fourth face portion and the fifth face portion.
 7. The ceramic electronic component according to claim 1, wherein the recess portion viewed from the second direction is rectangular.
 8. The ceramic electronic component according to claim 1, wherein the recess portion viewed from the second direction is V-shaped.
 9. The ceramic electronic component according to claim 1, wherein the recess portion viewed from the second direction is U-shaped.
 10. The ceramic electronic component according to claim 1, wherein the third direction dimension of the component body is within a range of 60 to 120 μm.
 11. The ceramic electronic component according to claim 1, wherein the third direction dimension of the component body is within a range of 25 to 60 μm.
 12. The ceramic electronic component according to claim 1, wherein first direction dimensions of the second face portion and the third face portion are larger than the first direction dimensions of the fourth face portion and the fifth face portion.
 13. The ceramic electronic component according to claim 1, wherein the ceramic electronic component includes a multilayer ceramic capacitor.
 14. The ceramic electronic component according to claim 13, wherein a capacitance value of the ceramic capacitor is within a range of 0.1 to 0.3 μF.
 15. The ceramic electronic component according to claim 13, wherein the capacitance value of the ceramic capacitor is within a range of 0.3 to 1.0 μF.
 16. A manufacturing method for a ceramic electronic component having external electrodes on each of opposed end portions of a rectangular parallelepiped component body, under a condition that a facing direction of opposed two faces of the component body is defined as a first direction, a facing direction of other opposed two faces is defined as a second direction, and a facing direction of the remaining opposed two faces is defined as a third direction, and dimensions along the respective directions are defined as a first direction dimension, a second direction dimension and a third direction dimension, respectively, the first direction dimension, the second direction dimension and the third direction dimension of the component body satisfying a condition of second direction dimension >first direction dimension >third direction dimension, the external electrodes being of a five-face type having a first face portion formed on one face in the first direction of the component body, a second face portion and a third face portion formed on a part of two faces in the third direction of the component body, and a fourth face portion and a fifth face portion formed on a part of two faces in the second direction of the component body, at least one edge of the fourth face portion and the fifth face portion of the external electrode having a recess portion recessed from the edge toward the first face portion, both side portions in the third direction of the recess portion being covering portions which cover ridge portions of the two faces in the second direction of the component body, wherein a process for producing the external electrodes includes: forming, on a surface of the component body, a base conductor layer corresponding to the first face portion, the second face portion and the third face portion, and a fourth face portion and a fifth face portion having the recess portions and the covering portions; and forming, on the surface of the base conductor layer, at least one covering conductor layer.
 17. The ceramic electronic component manufacturing method according to claim 16, wherein the number of the covering conductor layers is two or more, and a second and subsequent covering conductor layers are sequentially formed on a surface of the antecedently formed covering conductor layer.
 18. A ceramic electronic component-mounting circuit board, wherein a ceramic electronic component is mounted on a circuit board, the ceramic electronic component having external electrodes on each of opposed end portions of a rectangular parallelepiped component body, under a condition that a facing direction of opposed two faces of the component body is defined as a first direction, a facing direction of other opposed two faces is defined as a second direction, and a facing direction of the remaining opposed two faces is defined as a third direction, and dimensions along the respective directions are defined as a first direction dimension, a second direction dimension and a third direction dimension, respectively, the first direction dimension, the second direction dimension and the third direction dimension of the component body satisfying a condition of second direction dimension >first direction dimension >third direction dimension, the external electrodes being of a five-face type having a first face portion formed on one face in the first direction of the component body, a second face portion and a third face portion formed on a part of two faces in the third direction of the component body, and a fourth face portion and a fifth face portion formed on a part of two faces in the second direction of the component body, at least one edge of the fourth face portion and the fifth face portion of the external electrode having a recess portion recessed from the edge toward the first face portion, both side portions in the third direction of the recess portion being covering portions which cover ridge portions of the two faces in the second direction of the component body.
 19. The ceramic electronic component-mounting circuit board according to claim 18, wherein the external electrodes are connected to a conductive pad of the circuit board using solder. 